Retrieve Characteristic Value

[danbujak]

I've added a custom service and a few characteristics on the nRF51822. How can I access the current value stored in one of those characteristic outside of a BLE event occurring? Say for example on a button press I want to turn on the LED corresponding to the value stored in a characteristic.

[Ulrich Myhre]

sd_ble_gatts_value_get(conn_handle, handle, p_gatts_value_t)

You need to store the handles set in the output variable from sd_ble_gatts_characteristic_add() to know which handle you should retrieve. If you have this, it's pretty straight-forward!

[danbujak]

Is this the correct function to use even if the characteristic exists on the device that I am trying to read it from? In other words no BLE communication is required and there's no conn_handle in my case. Do I just use BLE_CONN_HANDLE_INVALID and it'll pull the data from the local attribute table?

[Ulrich Myhre]

The link to the documentation explains this. BLE_CONN_HANDLE_INVALID should be used for everything except system attributes. This function is only local, so if I have understood your question correctly, then yes: This is the function you should use. It does not require any BLE communication to be available.